c.1967 BSA 499cc A50 Racing Motorcycle

Frame no. ED 273 Engine no. A50CDY 10Z

• Believed to be a 'works' engine and frame
• Ideal for historic racing events and parades
• Rear Airheart hydraulic braking and Fontana front

The BSA unit engines, designated A50 and A65 to indicate 500 and 650cc capacities respectively, were introduced in 1962 to replace the venerable and much-loved pre-unit A7 and A10 engines. Riders such as Tony Smith, Peter Brown, and Norman Hanks played their part in the racing development of the unit twins. The factory sent A50 twins to the Daytona 200 race in 1965, 1966, 1967, and 1968. Whilst much of the UK racing was with the 650 twins, there was little experience with the 500 version, and the results at Daytona were less than auspicious, with mechanical failures of one sort or another sidelining the majority of the bikes.

The vendor purchased the engine of this bike from Paul Ingham, a well-known figure on the classic scene for many years. It was one of two engines Ingham had purchased from Norman Hanks (former BSA Development Tester, and works-supported racer) and the engines (a 650 and a 500) both had 'works' characteristics. The vendor had an interest in the Daytona bikes from 1965 to 1968, and, conscious that only 500cc engines had been allowed in that event, obviously opted for that one, with the intention of using it to replicate a Daytona-type bike.

With only an engine to start with, he began to search for parts which were suitable for the project. After initially buying a standard frame, he was hunting for further parts when he spotted this frame at Stafford Show autojumble. It was labelled as a 'BSA Race frame' and showed many features which were seen on the Daytona bikes, and was numbered ED 273. He snapped it up, knowing that the Daytona bikes were all stamped ED (for Experimental Department) with three-digit serial numbers. He subsequently purchased an appropriate used oil tank, and the same supplier was able to provide the correct-type rear hub and Airheart rear brake caliper. The Airheart master cylinder was sourced in USA, the Fontana 4LS front brake was located, a period oil cooler found; the alloy fuel tank was made as a one-off copying the originals.

The top end of the engine was stripped and rebuilt, whilst the bottom end was sound, as was the gearbox. The engine was found to have eccentric rocker spindles for tappet adjustment, and the ignition system is an energy transfer arrangement, carburettors are Amal Grand Prix. The owner spoke to a number of people with knowledge of the Daytona machines, including Norman Hanks, Peter Brown, and Les Williams, endeavouring to make the bike as accurate as possible. It took approximately two years to assemble the correct component parts, and a further year to build the bike. When it was assembled, the vendor started the machine, but it was not running correctly. Believing the fault to be the ignition system, he purchased two new coils for the energy transfer system, but never fitted them (included with the bike). He intended to use the A50 for sprints and parades, but his domestic circumstances have altered, and age is now a factor in his decision to dispose of the machine which will require some degree of commissioning prior to use. Documentation comprises miscellaneous papers, notes, and copies of photographs.
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